Thermal spraying process is generally referred to as a process that uses heat to deposit molten or semi-molten materials onto a substrate to protect the substrate from wear and corrosion. In a thermal spraying process the material to be deposited is supplied in a powder form, for example. Such powders could comprise small particles, e.g., between 100-mesh U.S. Standard screen size (149 microns) and about 2 microns.
A thermal spraying process generally includes three distinctive steps: the first step is to melt the material, the second is to atomize the material, and the third is to deposit the material onto the substrate. For example, an arc spraying process uses an electrical arc to melt the material and a compressed gas to atomize and deposit the material onto a substrate.
Materials known as hard facing alloys could be used for coatings produced, for example, by thermal spraying. Generally, the alloy coatings are used for hard surfacing to provide wear resistance, particularly where a desirable surface finish is desired. However, many coatings designed to operate at elevated temperatures and provide corrosion and wear properties often fail due to poor coating density, which leads to the corrosive products reaching the substrate and causing spalling. For example, composite coatings designed for wear protection often fail due to matrix erosion, leading to a loss of a composite hard phase. Accordingly, a need exists for improved materials to be used in thermal spray coatings.